Light scattering from a rough metal surface: theory and experiment

There is still great interest in the determination of microtopographic properties of rough metallic surfaces from light scattering measurements. According to Beckmann–Kirchhoff theory a clear relationship is established between the in-plane angular scattered light intensity and the statistical properties of the surface. We discuss one way to invert this relationship, and we introduce a new iterative procedure to retrieve the height autocorrelation function even for a very rough metallic surface (rms surface roughness of the same order of the optical wavelength). The procedure is eventually applied to the experimental data of a known metallic surface for validation

Scattering Lens Resolves sub-100 nm Structures with Visible Light

The smallest structures that conventional lenses are able to optically resolve are of the order of 200 nm. We introduce a new type of lens that exploits multiple scattering of light to generate a scanning nano-sized optical focus. With an experimental realization of this lens in gallium phosphide we have succeeded to image gold nanoparticles at 97 nm optical resolution. Our work is the first lens that provides a resolution in the nanometer regime at visible wavelengths.Comment: 4 pages, 3 figure

Algorithmic Embeddedness and the ‘Gig’ Characteristics Model: Examining the Interplay between Technology and Work Design in Crowdwork

This article systematically reviews the literature on online task crowdwork to investigate the complex relationship between technology and work design on crowdwork platforms. We highlight the diverse interpretations and uses of technology, specifically platform features and algorithms, in relation to work design. Our review reveals that platform features serve as antecedents to work design characteristics, while algorithms are so intertwined with job execution that a new work characteristic is needed to model this interplay. We introduce this new work characteristic as algorithmic embeddedness and show that it varies in degree. When high, algorithmic embeddedness can be perceived as either an affordance or a constraint; when low, it has a limited impact on crowdworkers' jobs. Our 'gig characteristics model' expands previous work design theories and offers a framework for understanding the design of contemporary jobs that rely highly on algorithms. To refine our model and better understand crowdwork dynamics, we provide an agenda for future research directions

2030 International RHIZomatic Assembly (IRHIZA)

In an interactive design fiction performance we ex- plore the notion of non-human intelligences and their active agency in political discourse. Through speculati- ve means a future context serves as both backdrop and design space for debates between humans and plants, exploring how the scientifically envisioned increased means of communication between the two could sha- pe new solutions and realities. The performance hence deals with an expanded notion of “participation” and debate beyond mere human actors. In a multidiscipli- nary setting, participants stemming from both design and other fields of research (e.g. (ethno)botany, (neuro) biology, anthropology, etc.) will engage in a role-play and joint speculative storytelling effort aimed at explo- ring new questions regarding the challenges and oppor- tunities shaped by such a future world

A kinetic study on the photodynamic properties of the xanthene dye merbromin (mercurochrome) and its aggregates with amino acids in aqueous solution

The photophysical properties and the photobleaching of the xanthene dye merbromin(MR), as well as the production and quenching of singlet molecular oxygen, O₂(¹∆g), were investigated in aqueous solutions, in comparison with the xanthene dyes eosine (Eos) and rose bengal (RB). MR photobleaches in the absence of O₂ in a process involving the solvent (H₂O or alcohols). No participation of O₂ or O₂(¹∆g) could be established in the presence of O₂, although O₂ Is consumed. In aqueous and alcoholic solutions, MR forms ground state charge transfer (CT) complexes with biologically relevant electron donor amino acids, such as histidine, thyptophan, and other indolic derivatives. These complexes are formed with relatively high association constants (3 x 10³ - 5 x 10³) and are mainly responsible for the photobleaching of MR and the amino acids in these solutions by a mechanism involving O₂(¹∆g) generated probably by an excited state of the CT complex. MR generates O₂(¹∆g) with a relatively high yield (Φ ∆= 0.23 ± 0.04) and quenches O₂(¹∆g) only physically with = (2.3 ± 0.05) 108 M⁻¹ s⁻¹. This process does not affect the photosensitizing ability of MR under the low concentrations needed for its action. Non-donor compounds like the amino acid methionine and linoleic acid methyl ester are photodegraded by a Type II mechanism without implication of a dye CT complex.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Filtering and Modulation from Visible to Terahertz using Phase-Change Extraordinary Optical Transmission Metasurfaces

This is the final version.Periodic arrays of sub-wavelength-scale holes in plasmonic metal films are known to provide resonant transmission/reflectance peaks via the extraordinary optical transmission (EOT) effect. Active control of the spectral position of such transmission/reflection peaks can be obtained by adding a layer of phase-change material (PCM) to the EOT device. Switching the PCM layer between its amorphous and crystalline states shifts the spectral position (and usually the amplitude too) of the resonance, so enabling potential applications in the fields of active filtering and sensing (e.g. for multispectral imaging) and optical modulation. Here we report the design, fabrication and characterization of active EOT devices targeted at various important regions of the optical spectrumEngineering and Physical Sciences Research Council (EPSRC

Phase-Change Extraordinary Optical Transmission Metasurfaces for Active Filtering and Modulation from the Visible to Terahertz Regimes

This is the final version. Available from META Conference via the link in this recordPeriodic arrays of sub-wavelength-scale holes in plasmonic metal films can designed to provide resonant transmission/reflectance peaks via the extraordinary optical transmission (EOT) effect. The addition of phase-change materials (PCMs) to such devices can provide a degree of tuneability, cycles of heating and quenching shifting the peak position and/or amplitude depending on the phase-state of the PCM layer. This opens up new application potential in the fields of active filtering and sensing (e.g. for multispectral imaging), displays and optical modulation.Engineering and Physical Sciences Research Council (EPSRC)Qineti

Oral naltrexone treatment for cholestatic pruritus: A double-blind, placebo-controlled study

Background and Aims: The efficacy of currently available therapeutic agents for cholestatic pruritus is often disappointing. The aim of this study was to assess the antipruritic effect of naltrexone, an oral opiate receptor antagonist. Methods: Sixteen patients with pruritus of chronic cholestasis were randomized to receive naltrexone (4-week course of 50 mg naltrexone daily) or placebo. Pruritus, quality of sleep, fatigue (using visual analogue scales), side effects, and liver function were assessed every 2 weeks. Serum naltrexone and 6β-naltrexol concentrations in all patients and 5 healthy controls were measured during the first day of naltrexone treatment. Results: Mean changes with respect to baseline were significantly different, in favor of the naltrexone group, for daytime itching (-54% vs. 8%; P = 0.001) and nighttime itching (-44% vs. 7%, P = 0.003). In 4 naltrexone-treated patients, side effects (transient in 3 cases) consistent with an opiate withdrawal syndrome were noted. No deterioration of the underlying disease was observed. Naltrexone and 6β-naltrexol levels did not differ between patients and controls, and there was no significant association with treatment response. Conclusions: For patients with cholestatic liver disease and itching, refractory to regular antipruritic therapy, oral naltrexone may be an effective and well-tolerated alternative